﻿using Microsoft.Extensions.DependencyInjection;
using System.Reflection;

namespace KxApp.Utils
{
    public static class DependencyExtension
    {
        /// <summary>
        /// 获取class, 非抽象类, 特性有ExposedServiceAttribute 注解
        /// </summary>
        /// <param name="services"></param>
        /// <returns></returns>
        //private static List<Type> GetTypes(Assembly assembly)
        //{
        //    var result = assembly
        //        .GetTypes()
        //        .Where(
        //            t =>
        //                t != null
        //                && t.IsClass
        //                && !t.IsAbstract
        //                && t.CustomAttributes.Any(
        //                    p => p.AttributeType == typeof(ExposedServiceAttribute)
        //                )
        //        )
        //        .ToList();

        //    return result;
        //}

        private static List<Type> MyGetTypes()
        {
            //获取当前程序集
            var entryAssembly = Assembly.GetEntryAssembly();
            var types = entryAssembly!
                .GetReferencedAssemblies() //获取当前程序集所引用的外部程序集
                .Select(Assembly.Load) //装载
                .Concat(new List<Assembly>() { entryAssembly }) //与本程序集合并
                .SelectMany(x => x.GetTypes()) //获取所有类
                .Where(
                    t =>
                        t != null
                        && t.IsClass
                        && !t.IsAbstract
                        && t.CustomAttributes.Any(
                            p => p.AttributeType == typeof(ExposedServiceAttribute)
                        )
                )
                .Distinct() //排重
                .ToList();
            ;

            return types;
        }

        //public static void RegisterAssembly(this IServiceCollection services, Assembly assembly)
        //{
        //    var list = GetTypes(assembly);
        //    foreach (var type in list)
        //    {
        //        RegisterAssembly(services, type);
        //    }
        //}

        /// <summary>
        /// 加this 表示 IServiceCollection 的扩展方法
        /// </summary>
        /// <param name="services"></param>
        public static void RegisterAssembly(this IServiceCollection services)
        {
            var list = MyGetTypes();
            foreach (var type in list)
            {
                RegisterAssembly(services, type);
            }
        }



        public static void RegisterAssembly(IServiceCollection services, Type type)
        {
            var list = GetExposedServices(type).ToList();

            foreach (var item in list)
            {
                switch (item.Lifetime)
                {
                    case Lifetime.Singleton:
                        services.AddSingleton(type);
                        break;
                    case Lifetime.Transient:
                        services.AddTransient(type);
                        break;
                    case Lifetime.Scoped:
                        services.AddScoped(type);
                        break;
                    default:
                        break;
                }

                foreach (var IType in item.Types)
                {
                    switch (item.Lifetime)
                    {
                        case Lifetime.Singleton:
                            services.AddSingleton(IType, type);
                            break;
                        case Lifetime.Transient:
                            services.AddTransient(IType, type);
                            break;
                        case Lifetime.Scoped:
                            services.AddScoped(IType, type);
                            break;
                        default:
                            break;
                    }
                }
            }
        }

        /// <summary>
        /// 初始化程序集中所有标注为ExposedServiceAttriubute特性的类，要求单例具自动加载AutoInitialize=true
        /// </summary>
        /// <param name="services"></param>
        /// <param name="assembly"></param>
        public static void InitializeAssembly(this IServiceCollection services)
        {
            var list = MyGetTypes();

            foreach (var item in list)
            {
                InitializeAssembly(services, item);
            }
        }

        private static void InitializeAssembly(IServiceCollection services, Type type)
        {
            var list = GetExposedServices(type);

            foreach (var item in list)
            {
                if (item.Lifetime == Lifetime.Singleton && item.AutoInitialize)
                {
                    services.AddSingleton(
                        type,
                        sp =>
                        {
                            return sp.GetRequiredService(type);
                        }
                    );
                }
            }
        }

        private static IEnumerable<ExposedServiceAttribute> GetExposedServices(Type type)
        {
            var typeInfo = type.GetTypeInfo();
            return typeInfo.GetCustomAttributes<ExposedServiceAttribute>();
        }
    }
}
